Capacitors are widely used in application areas, such as industrial appliances, medicine, automobiles, aircraft, space, power supply circuits, computers, power electronics, and energy storage. Of the myriad of applications, electronic components and energy storage devices, in particular, require the use of materials with high performance dielectric properties.
Electroactive polymers have shown promise for energy storage due to their excellent properties. Using poly(vinylidene fluoride) (PVDF) as an example, it is an electroactive thermoplastic polymer having excellent chemical resistance, good stability, high volume resistivity, low water absorption rate with potential pyroelectric, piezoelectric, and ferroelectric properties. Specifically, PVDF provides the best polymer ferroelectric property and the highest dielectric constant among all polymers. Notwithstanding the above, its dielectric constant is far lower than that of non-polymer counterpart such as dielectric ceramics. To qualify PVDF for use in high charge-storage capacitors or electrostriction system for artificial muscles, for example, there is a need to improve the dielectric constant of PVDF.
A number of methods have been used to improve the dielectric properties of PVDF. For example, the dielectric properties of PVDF may be improved by incorporating perovskite ceramic particles of high dielectric constants into the polymer. Although the dielectric constant of such polymer-ceramic composites has been found to be higher than that of pristine PVDF, polymers, unsatisfactory dielectric loss and low breakdown field strength of the composites have limited their application. Furthermore, high volume content of the ceramic fillers in the polymer contributes to a loss in flexibility, and lowers quality of the composites.
Apart from the use of perovskite ceramic particles, other additives such as metal particles and carbon nanotubes have been introduced into the polymers by physical blending. However, this approach suffers from drawbacks such as adverse excessive agglomeration of fillers due to the incompatibility of these fillers with the polymer matrix, which in turn leads to dielectric loss and reduction of breakdown field.
In view of the above, there is a need for a material with improved dielectric properties which addresses at least one of the above-mentioned problems.